TULOU or earthern buildings are found in Fujian Province in Southern China. I saw them when I visited the area in July 2011. The photos help, but seeing is believing. Di.

A tulou or "earthen building", is a traditional communal residence in theFujianprovince of Southern China, usually of a circular configuration surrounding a central shrine. These vernacular structures were occupied by clan groups.

Although most tulou were of earthen construction, the definition "tulou" is a broadly descriptive label for a building type and does not indicate construction type. Some were constructed of cut granite or had substantial walls of fired brick. Most large-scale tulou seen today were built of a composite of earth, sand, and lime known as sanhetu rather than just earth. The tulou is often three to four stories high. Often they would store food on the higher floors.

The famous Fujian Tulou, designated as UNESCO World Heritage site in 2008, is a small and specialized subgroup of tulou, and are known for their unique shape, large scale, and ingenious structure. There are more than 20,000 tulou in southern Fujian. Approximately 3,000 of them are Fujian Tulou, that is 15% of tulou belongs to Fujian Tulou category.

Early publications on tulous (the first of which appeared in a journal of Nanjing Institute of Technology in 1957) talked about tulous as the homes of Hakka people, primarily in Yongding County of southwestern Fujian. However, by the 1980s a substantial amount of research was also published on the tulous of the Hakkas' neighbors, the Southern Fujian people (known in Chinese as the Minnan people).[2] Those are primarily found in to the east of Yongding, in particular in in Nanjing County and Pinghe County of southeastern Fujian.[6]

Parts of Hakka tulou belong to the Fujian Tulou category. While all south Fujian tulous belong to the Fujian Tulou category, they do not belong to "Hakka Tulou". In effect, "Fujian Tulou" is not a synonym for "tulou", but rather a special subgroup of the latter. There are more than 20,000 tulous in Fujian, while there are only around three thousand "Fujian Tulou" located in southwestern region of Fujian province, mostly in the mountainous regions of Yongding County of Longyan City and Nanjing County of Zhangzhou City. Fujian Tulou is however the official name adopted by UNESCO for all dwellings of this type.

Based on the literal meaning of the Chinese words tu (土; "earth") and lou (樓; "[tall] building"), one may think of the term "tulou" as a generic description of a rammed-earth building. However, this would not be a useful definition, since, as the scholar of China's traditional architecture Huang Hanmin notes, rammed-earth building of one kind or another can be found in virtually all parts of China. Instead, it is preferable to use the definition actually used in Fujian: a tulou is a large building, constructed with load-bearing rammed earth walls, and used as a residence by a community (a group of families).[7] The first part of the definition contrasts tulous with structures that merely use rammed earth around the load-bearing wooden frame; the second part distinguishes tulous from small, single-family residencies.[7]

Based on the above definition, Huang Hanmin believes that out of the great variety of rammed-earth vernacular architecture of China, only the following regional styles, all associated with either Hakka or Minnan people, can be called "tulou" (at least in Chinese):[8][9]

"Guangdong tulou": the weilongwu (围龙屋) compounds of the northern Guangdong, and the weiwu(围屋) compounds of the northeastern Guangdong;[8]

"Jiangxi tulou": the tuweizi (土围子) compounds of the southern Jiangxi;[8][10]

While the Guangdong and Jiangxi tulou (usually known is English as "fortified villages"[11] or Hakka walled village) are associated with the Hakka people, among the Fujian tulou there are several types, some of which are characteristic of the Hakka, and others, of the Minnan.[8]

For the specifically Fujian Tulou, Huang Hanmin gives the following definition: "A large multi storey building in southeast Fujian mountainous region for large community living and defense, built with weight bearing rammed earth wall and wood frame structure."[12]